1.Field of the Invention
The present invention relates to an organic electroluminescent device (hereinafter referred to as an organic EL device).
2.Description of the Background Art
In recent years, with the prosperity of information technology (IT), demands for thin type display devices that are of a thin type having a thickness of several millimeters and can perform full-color display have increased. As such thin type display devices, the development of organic EL devices has been advanced.
Examples of methods of realizing full-color display include a method using a red light emitting device, a green light emitting device, and a blue light emitting device (see JP-A-2001-93667, for example) and a method using a combination of a white light emitting device and color filters for transmitting monochromatic lights in the three primary colors. The white light emitting device includes a blue luminescent material and an orange luminescent material, to realize a white color by simultaneously emitting blue light emitted by the blue luminescent material and orange light emitted by the orange luminescent material.
When white luminescence is realized using the blue luminescent material and the orange luminescent material, however, high efficiency as a white color cannot be realized unless the blue light and the orange light are emitted at a high efficiency. In a conventional white light emitting device, the limit is a luminous efficiency of 10 cd/A (see J. kido, M. Kumura, K. Nagai, Science, 267, 1332, 1995, for example).
On the other hand, when a white light emitting device and color filters are combined to perform full-color display, a part of white light is absorbed by the color filters, so that light having a high luminance is not obtained. In a case where the white light emitting device and the color filters are combined to perform full-color display, therefore, the power consumption is higher and the luminance is lower, as compared with those in a case where the red light emitting device, the green light emitting device, and the blue light emitting device are used to perform full-color display.